AHD says "open to change; adaptable; an emotionally labile person", which would seem a positive trait. But OED confirms my reading that the word implies instability. To demonstrate that reading, I'll present more quotes than usual.

What he could positively diagnose is that Anna Nicole was "labile: all over the place with her mood very up and down" right before her daughter's birth and well before her own death.– Radar Online, NY, Feb 23, 2007

Being an American you are doubly handicapped. Your womanly sentimentality is compounded by your American frivolity … You American girls are so audacious, animated … [e]specially compared to our serene, self-effacing English girls. Clearly, you have been encouraged to indulge your ebullient, labile emotions to an excessive degree.– Connie Brockway, A Dangerous Man

… he [Shakespeare] wished to demonstrate in Romeo and Juliet how reckless, labile, and ephemeral the emotion of love is, especially in young people …– Diane Ackerman, A Natural History Of Love

What I do know is that people who were already labile -- more upset, more unstable -- are now even more labile.– Washington Post, Oct. 28, 2001

This message has been edited. Last edited by: wordcrafter, March 12, 2007 13:20

I learned the psychological meaning of it a while back, along with affect as a noun, describing one's facial expression indicating one's mood (i.e., a poker face is similar to having no affect). The great thing about labile is that many assume it to be somehow risque.

Last week's storm, which began around 2 am Wednesday morning, led some percipient professors to cancel classes early on at their discretion.– Middlebury Campus (VT), Feb. 21, 2007

[regarding the independence of the United States:] "The only way to keep us from setting up ourselves is to disunite us," young schoolmaster Adams had written in his percipient letter to Nathan Webb, and … dissolution remained the greatest single threat to the American experiment.– David McCullough, John Adams

also, as a noun: percipient – one who receives a telepathic impulse or message

This procedure can be used as a test of telepathy (a "sender" looks at each card while the "percipient" tries to discern its identity) …– Thomas Gilovich, How We Know What Isn't So

Today's word is often seen in the sense of "that wascally wabbit", but is rare in its original sense.

wabbit – Scottish: exhausted or unwell

Mothers, do you remember what it was like to have a newborn babe in the house?

"While Ian catches his mornin' nap, Mistress McKie, suppose ye join me in the kitchen. …" Neda looked down at her, compassion lining every feature. "Might that be a blithe pastime for a wabbit young mither?" "Aye." She rose to her feet, pressing her hands into the small of her back, stiff from too little sleep.– Liz Curtis Higgs, Fair Is the Rose

Today, a very obscure word of new-motherhood. It is similar and related to a familiar word of very different meaning, which may help you remember it.

An ancient, knowing no astronomy, would see in the night sky pinpoints of light sprinkled in a dark background. He'd soon notice that those pinpoints are always in the same pattern, night after night, not moving relative to each other. Despite a few moving objects (the obvious moon [a non-pinpoint], a few planets, the occasional comet, and fast-flashing meteors), the general pattern is fixed points of light. Finally, the pinpoints are randomly scattered across the sky, not forming obvious patterns like lines, circles, etc., or grouping to make clumps or vacant areas, beyond what you'd see in a random scattering.. . .But one anomalous object, though in a fixed position night after night, is not a pinpoint and is not matched by other like objects, randomly spread. It is a vague, irregular, milky-white band of light across the sky. The ancient Greeks called it galaxias or kyklos galaktikos, meaning "milky circle".. . .Today we know that the stars are in fact not randomly scattered: they cluster. Each cluster has millions or billions of stars, but the clusters are so far apart that the ancient's naked eye could see only in our own cluster. Now as it happens, our cluster is disc-shaped, and we are out near the edge of that disc. So the ancient would see more of the disc (more stars) if he looked in one particular direction – along its plane, rather than above or below it – especially if looking towards the disc's center. In that direction he would see so many stars that they blend into a milky band, the one he called the kyklos galaktikos. And that is why we call such a clump of stars a galaxy.

In other words, our word galaxy comes from the word for 'milk'; it is cognate to lactation. It thus connects with new mothers, and with today's word.

agalaxy – failure of lactation; failure of the due secretion of milk after childbirth

soporific – 1. drowsy 2. inducing drowsiness or sleep (noun: a drug or other thing that makes one drowsy)

The debate, not yet half over, then settled into a soporific argument over figures, especially on the economy.– Montreal Gazette, Mar. 14, 2007

I tipped my head back and felt the cold sea air on my cheeks. The rocking of the boat was soporific, the muted creak and hush of the wind in the sheets and the sails.– Philippa Gregory, The Other Boleyn Girl

Question for our readers, raised by the last quote:What is the difference between a sail and a sheet? Do we have any nautical experts out there?

But he tends to be far too loquacious, and his arguments are far too likely to divagate from the essential point. I, on the other hand, write with a more relaxed, friendly style, supplying facts, and reasonably developing cogent arguments.- ZDNet, Dec. 10, 2004

But the short story concentrates her strengths; the very conciseness of the form doesn't allow her to dawdle or divagate.– San Jose Mercury News, May 5, 2004

zeitgeber – an environmental cue (as the length of daylight, or the temperature) that helps to regulate an organism's biological clock

Unfortunately, three's no wonder pill for jet lag. Instead, you can speed up the adjustment process by helping out the zeitgebers (don't you love it? It's German for 'timegivers') … the most important ones being meal times, sleep times and exposure to bright light.– Isabelle Young, Lonely Planet Healthy Travel Asia and India

A 'zeitgeber' can be as simple as the 6 pm newscast.– Chicago Sun-Times, Dec. 11, 1988

I would have suspected that many cave or deep ocean dwelling creatures would be cathemeral. I recall hearing that there were studies with people in caves where their rest/activity cycle became significantly longer than 24 hours.

I found an interesting link here about circadian rhythms. This part was particularly relevant to our discussion:

quote:

By depriving people of light and other external time cues, scientists have learned that most people’s biological clocks work on a 25-hour cycle rather than a 24-hour one. But because sunlight or other bright lights can reset the SCN, our biological cycles normally follow the 24-hour cycle of the sun, rather than our innate cycle. Circadian rhythms can be affected to some degree by almost any kind of external time cue, such as the beeping of your alarm clock, the clatter of a garbage truck, or the timing of your meals. Scientists call external time cues zeitgebers (German for "time givers").

I hadn't known about our 25-hour biological clocks. I also found it interesting that blind people often have life-long sleeping problems because their retinas can't detect light.

quote:

I can truthfully say that never never never in my long and varied life have I ever given a moment's thought to the difference between zeitgebers and Circadian rhythm.

By depriving people of light and other external time cues, scientists have learned that most people’s biological clocks work on a 25-hour cycle rather than a 24-hour one.

I read a hypothesis somewhere that suggested that this was because, at the time when animal life started to evolve, the Earth's revolved more slowly, taking around 25 hours per revolution. I don't know whether I agree with the idea, though.

I experienced an example of this phenomenon. Where I used to live, in Southern Ohio, we had a lot of whipporwills. Listening to their calls from the patio as dusk fell was a sweet pleasure of summertime. The last few years I lived there, I noticed that no longer did I hear their calls only at twilight but at varying times, so I looked into it through the local OSU extension office. Turns out the whipporwills had become confused by all the dusk-to-dawn lighting people had installed out in rural areas.

By depriving people of light and other external time cues, scientists have learned that most people’s biological clocks work on a 25-hour cycle rather than a 24-hour one.

I read a hypothesis somewhere that suggested that this was because, at the time when animal life started to evolve, the Earth's revolved more slowly, taking around 25 hours per revolution. I don't know whether I agree with the idea, though.

Seems to me, that with gravitational drag and all, the planet's spin should be slowing down, not speeding up. I don't buy that one.

I think it more likely that a 25 hour cycle that is constantly reset allows an animal to better stay alert and take advantage of the extra daylight when the days get longer

While I agree with neveu about the planet slowing down, I disagree this is the cause for the 25-hour natural body rhythm. At 2ms per day per century, it takes 500 centuries for the rotation to slow down a second! At this rate, the rotation would have slowed down an hour after 43 million years! It seems unrealistic that evolution wouldn't correct such a minor thing after this lengthy period of time.

...to say nothing of the fact that the day would have been 23 hours long millions of years ago, not 25 hours.

I agree that evolution probably has had ample time to correct this mismatch. Either the mismatch causes no ill affects, or it actually provides a slight benefit. I was trying to come up with a reason why there might be a benefit. The idea that the mismatch might aid the animal in adjusting to different amounts of daylight/night as the seasons change is just a wild unresearched guess on my part.

As I said, it was a hypothesis I read a while ago and I've not researched it.

One thing that would have happened to the Earth's rotation in the early days of its existence is that it would have speeded up. The Earth started out as a large ball of gas that gradually coalesced and shrunk under the influence of gravity. As it shrunk its speed of rotation will have increased assuming the total amount of energy in the system remained constant; that is a basic fact of the physics of rotating bodies. Once the shrinkage had ended, then a gradual reduction of speed would occur - although with the amount of kinetic energy available and the relatively few constraints on motion, this would be a very small reduction.

Of course, the increasing speed phenomenon might well have long finished before life began; that's why I said I am not convinced by the hypothesis - but it is something that I might try to research.

But I suppose it might be possible that as the Earth captured the spin of the Moon some of that angular momentum might have been transfered to the Earth, although it is likely that that occurred before the advent of life as well.